An institution where I am currently a part-time employee has just asked me to fill out a W-9 form for a 1-week summer event I am working in a few days, concurrently with the regular hours I work each week. They are asking me to send an invoice for all hours I work during this summer event.

I signed a W-4 when I was hired a year ago and they withhold taxes from my regular paycheck. I don't understand why the same institution where I am regularly employed is asking me to be considered a freelancer/independent contractor for this, as I will end up paying more on self-employment taxes. They claim the W-9 is needed because the payment for this particular program comes from a "separate account" dedicated to the staffing of this event.

Furthermore I have worked the same program in past years and was always on payroll, and actually paid a much higher hourly rate. I've speculated that there may have been budget cuts in my department recently but it seems as though they are making this up as they go along. What instances if any make it legal to do this?

I signed a W-4 when I was hired a year ago and they withhold taxes from my regular paycheck. I don't understand why the same institution where I am regularly employed is asking me to be considered a freelancer/independent contractor for this, as I will end up paying more on self-employment taxes.====>>>>>>>>>Correct
They claim the W-9 is needed because the payment for this particular program comes from a "separate account" dedicated to the staffing of this event.

Furthermore I have worked the same program in past years and was always on payroll, and actually paid a much higher hourly rate. I've speculated that there may have been budget cuts in my department recently but it seems as though they are making this up as they go along. What instances if any make it legal to do this?===========>>>>>>>>In my opinion, you are a regular W2 employee NOT an IC receiving 1099; On W2 your employer must withhold income and Social Security and Medicare taxes. On 1099-misc, you will pay 15.3% SE tax instead of 7.65% withheld from W2 income. Thus you pay about 7.5% more even if you claim 50% of SECA taxes on your 1040 page 1 line 27 .
there's always risk in confronting an employer when faced with a situation like yours . most employers know full well that they are violating the law when they treat employees as independent contractors, and for that reason they don't tolerate questions about that policy very well . so you definitely should tread cautiously if you want to keep this position. I guess you may file Form SS-8 that will cause the IRS to contact your employer to get his side of the questions. If it's determined that you are really an employee rather than an independent contractor, your boss will have to pay his half of your FICA and Medicare taxes. It won't affect your income tax. It MAY really upset your boss. You MIGHT find yourself out of work. I'm not saying don't file it. I'm just saying be sure you understand the possible consequences. The people I know generally wait till they have found other work before they file it. So, He doesn't need W9 . You may ask him what the purpose is for it.